1. Field
The present invention relates generally to communications and more particularly, to a method and apparatus for interworking between push-to-talk over cellular (PoC) systems and instant messaging (IM) systems.
2. Background
Wireless communication systems have seen significant growth in recent years with increases in subscribers and utilization. This growth has prompted operators to seek to offer additional features and services to subscribers. Examples of new features that many operators offer to subscribers include: music downloads, video services, push-to-talk over cellular (PoC), and instant messaging service (IM). PoC and IM services have been especially popular.
FIG. 1 is a block diagram that shows a Push-to-Talk over Cellular (PoC) service and an Instant Messaging (IM) service, both operating in a wireless communication system 100.
An Instant Messaging (IM) client 108 uses an IM service to exchange messages with other IM clients 108. Even though IM service was developed to exchange text based information, there is no restriction to carrying other types of information such as audio clips, images etc. Also, there is no restriction on a user regarding what to transmit and when to transmit. Typically the information is not streamed from the sender to receiver.
A Push-to-Talk over Cellular (PoC) service establishes a half-duplex audio communication channel between a group of PoC users or clients 104. At most one member of a PoC group has the right to transmit at any time and all other members receive the transmitted information. A floor control mechanism is used to arbitrate requests for the right to transmit from different members of the group. The talk burst generated by the sender is packetized and then streamed to the receivers.
Since it is possible to transmit audio clips using IM service, it would be beneficial if the PoC service could work with IM service. However, differences between these services have prevented a PoC service and an IM service from working together. Floor control is used in PoC service to ensure that only one client transmits audio packets at a time. In contrast, IM service has no concept of floor control, as each member of an IM group may transmit at any time. The PoC service packetizes the audio and then streams the audio to other participants. This is not the case in the IM service, where the IM client buffers the audio packets and creates an audio clip which is then distributed to other IM session participants. Since it is possible and desirable to transmit audio clips using the IM service it would be beneficial if the PoC service could work together with the IM service.
Thus, there is a need in the art for a method and apparatus for interworking between push-to-talk cellular systems and instant messaging systems.